(2) The evidence indicates that some workers may have accumulated substantial
chronic dose as a result of episodic occupational exposure to radionuclides,
combined with external exposures to gamma, beta, and potentially neutron
radiation.

(3) NIOSH did not identify any evidence from the petitioners or from other resources
that would establish that the class was exposed to radiation during a discrete
incident likely to have involved exceptionally high level exposures, such as a
nuclear criticality incident, as defined under 42 C.F.R. § 83.13(c)(3)(i).

(4) The Board concurred with the finding of NIOSH that the health of the class may
have been endangered and defined the class according to the 250-work day
requirement specified under 42 C.F.R. § 83.13(c)(3)(ii). The Board continues to
evaluate the potential of discrete incidents that could have involved exceptionally
high exposures to radiation and issues related to workers who may not meet the
250-work day requirement described above, and the Board may make additional
future recommendations accordingly.

V. — Effect and Effective Date of Designation

The Secretary submits this report on designation of one additional class to the SEC
for review by Congress, pursuant to 42 U.S.C. §§ 7384/(14)(C)(ii) and
7384q(c)(2)(A), as amended by the Ronald W. Reagan National Defense
Authorization Act for Fiscal Year 2005, Pub. L. No. 108-375 (codified as amended in
scattered sections of 42 U.S.C.). Pursuant to 42 U.S.C. § 7384/(14)(C)(ii). as
amended by the Ronald W. Reagan National Defense Authorization Act for Fiscal
Year 2005, Pub. L. No. 108-375 (codified as amended in scattered sections of 42
U.S.C.), the designation in this report will become effective 30 days after the date of
this report’s submission to Congress ‘unless Congress otherwise provides.”

VI. Administrative Review of Designation

The health endangerment determination of the designation provided in this report
may be subject to an administrative review within HHS, pursuant to 42 C.F.R. §
83.18(a). On the basis of such a review, if the Secretary decides to expand the class
of employees covered by this designation, the Secretary would transmit a
supplementary report to Congress providing the expanded employee class definition
and the criteria and findings on which the decision was based.

HHS Special Exposure Cohort Designation:
Ames Laboratory


HHS Designation of Additional Members of the

Special Exposure Cohort
under the

Energy Employees Occupational Illness Compensation Program Act

Designating a Class of Employees from

Ames Laboratory
Ames, Iowa

HHS Special Exposure Cohort Designation:
Ames Laboratory


I. Designation

1, Michael O. Leavitt, Secretary of Health and Human Services (“the Secretary”),
designate the class of employees defined in Section II of this report for addition to the
Special Exposure Cohort (SEC), as authorized under the Energy Employees
Occupational I!Iness Compensation Program Act of 2000 (EEOICPA), 42 U.S.C. §
7384q.

AUG - 8 2006

v
Date Michael O. Leavitt

II. _ Employee Class Definition

Department of Energy (DOE) employees or DOE contractor or subcontractor
employees who worked at the Ames Laboratory in one or more of the following
facilitics/locations: Chemistry Annex | (also known as “the old women’s
gymnasium” and “Little Ankeny”), Chemistry Annex 2, Chemistry Building (also
known as “Gilman Hall”), Research Building. or the Metallurgical Building (also
known as “Harley Wilhelm Hall”) from January 1, 1942 through December 31, 1954
for a number of work days aggregating at least 250 work days, or in combination with
work days within the parameters (excluding aggregate work day requirements)
established for one or more classes of employees in the SEC, and who were
monitored or should have been monitored.

III. Designation Criteria and Recommendations

Pursuant to 42 U.S.C. § 7384q, for the class defined in Section II of this report, the
Secretary has determined, and the Advisory Board on Radiation and Worker Health
(‘the Board”) has recommended, that
(1) it is not feasible to estimate with sufficient accuracy the radiation dose that the
class received, and
(2) there is a reasonable likelihood that such radiation dose may have endangered
the health of members of the class.

The SEC final rule states in 42 C.F.R. § 83.13(c)(1) that it is feasible in two situations
to estimate the radiation dose that the class received with sufficient accuracy. First.
the rule states that radiation doses may be estimated with sufficient accuracy if
NIOSH has established that it has access to sufficient information to estimate the
maximum radiation dose for every type of cancer for which radiation doses are
reconstructed that could have been incurred under plausible circumstances by any
member of the class. Alternatively, radiation doses may be estimated with sufficient
accuracy if NIOSH has established that it has access to sufficient information to
estimate the radiation doses of members of the class more precisely than a maximum
dose estimate.

HHS Special Exposure Cohort Designation:
Ames Laboratory


The Board, pursuant to 42 U.S.C. § 7384q. advised the Secretary to designate the
class as an addition to the SEC in a letter dated July 5, 2006 and received by the
Secretary on July 6, 2006.

IV. Designation Findings

Feasibility of Estimating Radiation Doses with Sufficient Accuracy

The Secretary established the feasibility determination for the class of employees
covered by this report upon the findings summarized below.

(1) The sum of information from the available resources is not sufficient to document
or estimate the potential maximum internal and external exposure to members of
the class under plausible circumstances during the period of radiological
operations at the Ames Laboratory.

(2) Although NIOSH has determined that doses from exposures to uranium
production and casting can be reconstructed, exposures resulting from production
and casting of thorium metal during 1953 and 1954 cannot be reconstructed.

(3) Pursuant to 42 C.F.R. § 83.13(c)(1), NIOSH determined that there is insufficient
information either to estimate the maximum radiation dose for every type of
cancer for which radiation doses are reconstructed that could have been incurred
under plausible circumstances by any member of the class, or to estimate the
radiation doses of members of the class more precisely than a maximum dose
estimate.

(4) NIOSH determined that it is possible to reconstruct or bound the occupational
required medical doses.

Health Endangerment

The Secretary established the health endangerment determination for the class of
employees covered by this report upon the findings summarized below.

(1) Pursuant to 42 C.F.R. § 83.13(c)(3), NIOSH established that there is a reasonable
likelihood that such radiation doses may have endangered the health of members
of the class. Pursuant to 42 C.F.R. § 83.13(c)(3)(ii), NIOSH specified a minimum
duration of employment to satisfy this health endangerment criterion as “having
been employed for a number of work days aggregating at least 250 work days
within the parameters established for this class or in combination with work days
within the parameters (excluding aggregate work day requirements) established
for one or more other classes of employees in the Cohort.”

HHS Special Exposure Cohort Designation:
Ames Laboratory